[paul245]

Gooday

What is the general category reaction of carbonation? Is it a metathesis reaction?

[sjb]

What do you mean by carbonation? My understanding of methathesis is more along the lines of things like http://en.wikipedia.org/w/index.php?title=Ring-closing_metathesis&oldid=272445162 - is there a more general reaction that goes by this name?

[paul245]

My apologies,

My question refers to the carbonation of calcium. Specifically, when calcium carbonate is precipitated from a solution of calcium hydroxide as per :

Ca(OH)2 + CO2 → CaCO3 + H2O

All the preciptation reactions that I know of are metathesis but I'm not 100% sure about this one. Is it metathesis or is it something else? Any help would be most welcome.

[paul245]

Hi All

Please allow me to put my question differently in order that it may be better understood:

Please can some one tell me if if the following reaction is a metathesis reaction or if not, what general form of reaction it is.

Ca(OH)2 + CO2 → CaCO3 + H2O

The wiki page is here:http://en.wikipedia.org/wiki/Carbonatation

I know it is a precipitation reaction and many precipitation reactions are metathesis but I thought metathesis involves an exhange of ions from both sides between two ionic substances but here we have co2 which is molecular and Ca(OH)2 which is ionic which leaves me confused. Please help.

[Rabn]

The key to solving your problem here is to remember that you're working in an aqueous environment.  what do you know about how CO₂ behaves in an aqueous environment?

[paul245]

As far as I understand CO2 will dissolve in water but because it is molecular it will not ionize? I'm not too sure where you are going with this. So what does happen when CO2 is in aqueous solutions?

[Vidya]

http://en.wikipedia.org/wiki/Metathesis_reaction_(chemistry)#Acid_and_carbonates
Read it carefully.

[paul245]

That's fatastic! Thanks a lot. I really do appreciate it.